If you are using Google Analytics for WordPress by MonsterInsights and encountered an error ” No HTTP response detected and Missing analytics.js script “ using the Chrome Google Tag Assistant by Google extension, that is quite normal. The reason why you are encountering that error is because you are loghed into your WordPress website and Monster Insights Analytics does not return an http response while you are logged as an Administrator or Editor by default.
In order to fix the issue or check if the analytics is properly working, all you have to do is log out of your WordPress site and then run the Google Tag Assistant. Another option to fix it without logging out is to go to plugin settings. Go to Insights > Settings then click the Tracking Tab then under engagement, remove the administrator role.